Square D (Schneider Electric) ZB4BV6 Harmony Light Block. Telemecanique Lamp Module, Series: Harmony XB4, 22 mm Size, BA9s Lamp, 250 VAC, Screw Clamp Terminal, Chrome, 1.85 in H x 1.18 in W x 1.46 in D Dimensions. Additional Description: SQD -ZB4BV6 Mtg COLLAR WITH DIRECT SUPPLY LIGHT MOD SUPPLY LIGHT MOD LIGHT MOD & LIGHT MODULE. Catalog Description: Harmony XB4, Light block with body/fixing collar, metal, for BA9s bulb, <= 250 V.